Wheat rust epidemics damage Ethiopian wheat production: A decade of field disease surveillance reveals national-scale trends in past outbreaks.

Wheat rusts are the key biological constraint to wheat production in Ethiopia-one of Africa's largest wheat producing countries. The fungal diseases cause economic losses and threaten livelihoods of smallholder farmers. While it is known that wheat rust epidemics have occurred in Ethiopia, to date no systematic long-term analysis of past outbreaks has been available. We present results from one of the most comprehensive surveillance campaigns of wheat rusts in Africa. More than 13,000 fields have been surveyed during the last 13 years. Using a combination of spatial data-analysis and visualization, statistical tools, and empirical modelling, we identify trends in the distribution of wheat stem rust (Sr), stripe rust (Yr) and leaf rust (Lr). Results show very high infection levels (mean incidence for Yr: 44%; Sr: 34%; Lr: 18%). These recurrent rust outbreaks lead to substantial economic losses, which we estimate to be of the order of 10s of millions of US-D annually. On the widely adopted wheat variety, Digalu, there is a marked increase in disease prevalence following the incursion of new rust races into Ethiopia, which indicates a pronounced boom-and-bust cycle of major gene resistance. Using spatial analyses, we identify hotspots of disease risk for all three rusts, show a linear correlation between altitude and disease prevalence, and find a pronounced north-south trend in stem rust prevalence. Temporal analyses show a sigmoidal increase in disease levels during the wheat season and strong inter-annual variations. While a simple logistic curve performs satisfactorily in predicting stem rust in some years, it cannot account for the complex outbreak patterns in other years and fails to predict the occurrence of stripe and leaf rust. The empirical insights into wheat rust epidemiology in Ethiopia presented here provide a basis for improving future surveillance and to inform the development of mechanistic models to predict disease spread.

Seroprevalence of Toxoplasma gondii in Nazaret town, Ethiopia.

OBJECTIVE: To determine the seroprevalence of toxoplasmosis, assess its zoonotic importance and identify factors associated with seroprevalence. METHODS: Questionnaire survey was conducted on 65 serum samples collected from male and female urban and peri-urban residents aged between 15 days and 65 years. Main outcome measures were feeding habits, purpose of keeping cats and association with family members. Serologic evidence of toxoplasmosis was conducted by the Modified Direct Agglutination Test (MDA T) and determination of HIV status using the HIV - Spot Test. RESULTS: Over 50% of the interviewed people had a history of consumption of raw or undercooked mutton and had close contact with cats. 60% of the serum samples analyzed by the MDA T had serologic evidence of Toxoplasma infection. Significantly higher MDA T tiers were encountered both in pregnant and immunocompromised individuals. The risk factors associated to Toxoplasma infection, i.e. raw or undercooked mutton consumption and presence of cats appeared significant. CONCLUSION AND RECOMMENDATIONS: The significance of toxoplasmosis as a disease of zoonotic importance was demonstrated. Close contact between family members and the consumption of raw or undercooked mutton were the major risk factors in the transmission of the disease. Considering the relatively high prevalence as revealed by this study it would be important to conduct studies on a wider scale. It would also be important to increase public awareness and upgrade the knowledge on congenital toxoplasmosis.

Seroprevalence of Toxoplasma Ghondii in Nazareth Town; Ethiopia

Objective: To determine the seroprevalence of toxoplasmosis; assess its zoonotic importance and identify factors associated with seroprevalence. Methods: Questionnaire survey was conducted on 65 serum samples collected from male and female urban and peri-urban residents aged between 15 days and 65 years. Main outcome measures were feeding habits; purpose of keeping cats and association with family members. Serologic evidence of toxoplasmosis was conducted by the Modified Direct Agglutination Test (MDA T) and determination of HIV status using the HIV - Spot Test. Results: Over 50of the interviewed people had a history of consumption of raw or undercooked mutton and had close contact with cats. 60of the serum samples analyzed by the MDA T had serologic evidence of Toxoplasma infection. Significantly higher MDA T tiers were encoun- tered both in pregnant and immunocompromised individuals. The risk factors associated to Toxoplasma infection; i.e. raw or undercooked mutton consumption and presence of cats appeared significant. Conclusion and recommendations: The significance of toxoplasmosis as a disease of zoonotic importance was demonstrated. Close contact between family members and the consumption of raw or undercooked mutton were the major risk factors in the transmission of the disease. Considering the relatively high prevalence as revealed by this study it would be important to conduct studies on a wider scale. It would also be important to increase public awareness and upgrade the knowledge on congenital toxoplasmosis

Seroprevalence of Toxoplasma gondii in Nazareth Town, Ethiopia.

OBJECTIVE: To determine seroprevalence of toxoplasmosis, assess its zoonotic importance and identify factors associated with seroprevalence. DESIGN: Questionnaire survey and serological studies. SUBJECTS: Questionnaire survey and 65 serum samples from male and female urban and peri-urban residents aged between 15 days and 65 years. MAIN OUTCOME MEASURES: Feeding habits, purpose of keeping cats and association with family members, serologic evidence of toxoplasmosis by the Modified Direct Agglutination Test (MDAT), examination of HIV status using the HIV-Spot Test. RESULTS: Over 86% of the interviewed people had a history of consumption of raw or undercooked mutton and had close contact with cats. Of the serum samples analyzed by the MDAT 60% had serologic evidence of Toxoplasma infection. Significantly higher MDAT tiers were encountered both in pregnant and immunocompromised individuals. The risk factors associated with Toxoplasma infection, i.e. raw or undercooked mutton consumption and presence of cats appeared significant. CONCLUSION AND RECOMMENDATIONS: The significance of toxoplasmosis as a disease of zoonotic importance was demonstrated. Close contact between family members and the consumption of raw or undercooked mutton were the major risk factors in the transmission of the disease. Considering the relatively high prevalence as revealed by this study it would be important to conduct studies on a wider scale. It would also be important to increase public awareness and upgrade the knowledge on congenital toxoplasmosis.

Comparison of in ovo and post-hatch vaccination with particular reference to infectious bursal disease. A review.

In ovo vaccination is an alternative approach to post-hatch vaccination of chickens, particularly in broilers. Vaccination at embryonation day 18 helps to 'close the window' of susceptibility i.e. the time between vaccination and early exposure to infectious agents compared with post-hatch vaccination. Attempts on embryonal vaccination as a mode of vaccine delivery were approached from the observation that chickens already develop certain immunologic functions before hatching. The immune system in birds begins to develop early during embryogenesis and various immune reactions have been induced in the late stage chicken embryos. Compared with post-hatch vaccination, in ovo vaccination stimulates both the innate and adaptive immune responses with the advantage that because of the prenatal immunization, in ovo vaccinated chicks have developed an appreciable degree of protection by the time of hatch. Effects of maternal antibodies on vaccines to be used for in ovo vaccination can be prevented by developing vaccines that are insensitive to maternal antibodies. It has been described that vaccination of chicken embryos at embryonation day 18 did not significantly affect the immune competence of hatched chickens. The apparent absence of tolerance in chicks hatched from embryos exposed to an antigen at the late stage of embryonation implies the feasibility of in ovo vaccination. Investigations on in ovo vaccination to produce safe and efficient vaccines are still in progress. Currently a large number of vaccines are under investigation for viral, bacterial and protozoal diseases.